OBJECTIVES: Traumatic brain injury (TBI) has high morbidity and mortality in both
civilian and military populations. Blast and other mechanisms of TBI damage the
brain by causing neurons to disconnect and atrophy. Such traumatic axonal injury
can lead to persistent vegetative and minimally conscious states (VS and MCS),
for which limited treatment options exist, including physical, occupational,
speech, and cognitive therapies. More than 60 000 patients have received vagus
nerve stimulation (VNS) for epilepsy and depression. In addition to decreased
seizure frequency and severity, patients report enhanced mood, reduced daytime
sleepiness independent of seizure control, increased slow wave sleep, and
improved cognition, memory, and quality of life. Early stimulation of the vagus
nerve accelerates the rate and extent of behavioral and cognitive recovery after
fluid percussion brain injury in rats.
METHODS: We recently obtained Food and Drug Administration (FDA) approval for a
pilot prospective randomized crossover trial to demonstrate objective improvement
in clinical outcome by placement of a vagus nerve stimulator in patients who are
recovering from severe TBI. Our hypothesis is that stimulation of the vagus nerve
results in increased cerebral blood flow and metabolism in the forebrain,
thalamus, and reticular formation, which promotes arousal and improved
consciousness, thereby improving outcome after TBI resulting in MCS or VS.
DISCUSSION: If this study demonstrates that VNS can safely and positively impact
outcome, then a larger randomized prospective crossover trial will be proposed.